Method of processing a synthetic resin tube, and tubular container

ABSTRACT

The technical problem of this invention is to establish a method of processing a synthetic resin tube, in which the shape of a part of the tube wall is changed to form easily an attractively hollowed and/or raised portion in a fairly wide area of the tube wall. The object of this invention is to provide a tubular container having excellent decorativeness, appearance, or functionality that has never been found before. A method of processing a synthetic resin tube comprises utilizing a mandrel having a mold portion, which has at least a shape selected from a hollowed shape, a raised shape, and a hollowed and raised shape formed in a part of outer surface of the mandrel, and which is also provided with small through-holes in this mold portion; inserting a bottomed cylindrical mandrel into a synthetic resin tube, while bringing the inner wall of the tube in contact with the mandrel; heating and softening the tube in the portion facing the mold portion; deaerating the tube via a central opening and the through-holes to mold the softened portion of the tube in a manner similar to vacuum molding; and forming in the tube wall at least one of the portions selected from a hollowed portion, a raised portion, and a hollowed and raised portion.

BACKGROUND

This invention relates to a method of molding a hollowed portion, araised portion, or a hollowed and raised portion in the body wall of atubular container or a tube made of a synthetic resin, which is to befilled with a food, tooth paste, a cosmetic, and the like, and to atubular container on which a hollowed and/or raised portion is formed.

Conventionally, tubular containers have been utilized to take out agiven quantity of a viscous material, such as tooth paste. The bodies ofthese tubular containers comprise a tube obtained by extruding asynthetic resin in a cylindrical shape, or a tube of film with longersides of the film joined together and adhered to each other. In manycases, laminated tubes are used, in which some resin layers arelaminated.

A head consisting of neck and shoulder is adhered to one end of saidtube, and the other end of the tube is thermally sealed. The finishedproduct is used as a tubular container. Patent Document 1 has adescription on a method of adhering the head to the tube.

As described above, the body of the tube is made and used by extruding asynthetic resin or resins in a cylindrical shape, or by joining andadhering longer sides of film together. In the case of ordinary tubularcontainers, the body is used in the flat, smooth state, without furtherprocessing. However, Patent Document 2 has descriptions on asurface-processed tubular container and on a method of producing such atubular container. This method comprises utilizing an integrally joinedtube prepared by rolling a synthetic resin sheet and thermally pressingtogether the overlap portions of the longer sides. When the lower end ofthe tube is heated and pressed for sealing, a pair of heating belts isused to emboss an up-and-down pattern from outside simultaneously withthe sealing operation. It is asserted that this up-and-down pattern canbe utilized for container recognition.

[Patent Document 1] Japanese Publication No. 1982-12739

[Patent Document 2] Japanese Application No. 1996-72905

SUMMARY

The method shown in Patent Document 2 involves embossing an up-and-downpattern on the tube surface within a limit of tube wall thickness.However, this method restricts the embossment only to a function forcontainer recognition. But in recent years, there is an increasing needfor a technology that can change the shape of a part of the containerbody wall to form an attractively hollowed, raised, and/or hollowed andraised portion (herein after referred to as a hollowed and/or raisedportion), which is aimed at differentiating the tubes in both aspects ofshape and function. In the shape aspect, the hollowed and/or raisedportion of the tubular container can be printed or labeled for adecorative effect to catch the eyes of people to a product on a displayrack. In the aspect of function, the hollowed and/or raised portion maybe provided with an up-and-down pattern that serves for a recognizingfunction and also makes it easy to hold the tube with a hand.

The technical problem of this invention is a method of processing atube, in which the shape of a part of cylindrical wall of the syntheticresin tube is changed to form easily an attractively hollowed and/orraised portion in a fairly wide area of the tube. The object of thisinvention is to provide a tubular container having excellentdecorativeness, appearance, or functionality that has not been foundbefore.

Among the means of this invention to solve the above-described technicalproblem, is a method of processing a synthetic resin tube, whichcomprises:

utilizing a bottomed cylindrical mandrel having a mold portion, whichhas at least a shape selected from a hollowed shape, a raised shape, anda hollowed and raised shape formed in a part of outer surface of themandrel, and which is also provided with small through-holes in thismold portion;

inserting the mandrel into a synthetic resin tube, while bringing innerwall of the tube in contact with the mandrel;

heating and softening said tube in the portion facing said mold portionunder the condition that the mandrel has been inserted in the tube;

deaerating the tube via a central opening and the through-holes of themandrel to mold the softened portion of the tube in a manner similar tovacuum molding; and

forming in the tube wall at least one portion selected from a hollowedportion, a raised portion, and a hollowed and raised portion.

The above-described method utilizes a bottomed cylindrical mandrelhaving a mold portion, which has at least a shape selected from ahollowed shape, a raised shape, and a hollowed and raised shape(hereinafter wholly referred to as the hollowed and/or raised moldportion) to be formed in a part of outer surface of the mandrel, andwhich is provided with small through-holes in this mold portion. Themandrel is inserted in the synthetic resin tube, and the inner surfaceof the tube is brought in contact with the mandrel. The tube is thenheated and softened in the portion facing the mold portion under thecondition that the mandrel has been inserted in the tube. This heatingoperation creates thermal shrinkage in the softened area. As a result,the periphery of the softened area of the tube wall comes in closecontact with the curved outer surface of the mandrel in the areasurrounding the mold portion. Because of this close contact, deaerationproceeds smoothly from the through-holes to the central opening of themandrel. The softened portion is molded in a manner similar tovacuum-molding so as to trace the shape of the mold portion. Therefore,it is possible to change the shape of a part of the tube wall and toform a hollowed and/or raised portion, rather than embossing anup-and-down pattern on the outer surface of the tube.

The synthetic resin tube is usually molded by extruding the syntheticresin in a cylindrical shape or by joining the longer sides of a filmtogether and adhering overlapped portions along these sides. When thetube is heated and softened, there occurs thermal shrinkage enough togive tightness in the above-described contact.

In the case of the molding carried out in a manner similar to vacuummolding, the softened resin deforms relatively uniformly because theresin is pulled from inside in all the softened area. There is nooccurrence of partially biased drawing, and the softened portion can bemolded so as to trace the shape of the mold portion, while minimizingwrinkle formation. Therefore, it is possible to mold an attractivelyhollowed and/or raised portion.

The tube is in the undercut engagement with the mandrel due to the shapeof the hollowed and/or raised portion that has been formed according tothe shape of the mold portion. This tube is squeezable and is made of arelatively soft synthetic resin to give a thin wall. After the hollowedand/or raised portion has been formed, the tube can be pulled andseparated from the mandrel relatively easily, though the undercutportion is deformed to some extent at the time of pull.

The method of forming a hollowed and/or raised portion according to thisinvention is applicable to both of single-layer and multi-layer tubularcontainers. This method is also applicable to laminated tubes in which athin film of a metal, such as aluminum, is sandwiched betweenpolyethylene layers in a polyethylene-aluminum-polyethyleneconfiguration.

The method according to one aspect of the invention comprises at leastone of the shapes of the hollowed and/or raised portion is formed in thetube wall in the manner similar to vacuum-molding and that a press diemade of a soft material is thrust onto the softened portion of the tubein the manner similar to press molding.

The softened portion of the tube is deformed to assume roughly the shapeof the hollowed and/or raised mold portion in an operation similar tovacuum molding. Then, the press die is thrust onto the softened portionin the manner similar to press molding. The hollowed and/or raisedportion is thus formed smoothly, with clear-cut edges being reproducibleprecisely.

If the press die were thrust onto the softened portion in the mannersimilar to press molding, without shaping first the hollowed and/orraised portion in the manner similar to vacuum molding, then thesoftened resin would deform disproportionately at the edges. In thatcase, wrinkles would develop, and it would not be able to form smoothlythe hollowed and/or raised portion having attractive appearance. But ifthe softened portion is first allowed to take roughly the shape of thehollowed and/or raised mold portion in an operation similar to vacuummolding before the softened portion is processed in the manner similarto press molding, then the hollowed and/or raised portion can be formedsmoothly, and highly reproducible, clear-cut edges would result.

The method according to another aspect of the invention comprisesutilizing a press die made of silicon rubber.

As the soft materials, various rubber materials can be utilized in theabove-described method. The press die of silicon rubber is suitablebecause of durability, fitness of the press die to trace the shape ofthe mold portion that has been hollowed and/or raised, and releasabilityfrom the softened area of the tube. Such a silicon rubber press dieimproves productivity and enables quite an attractively hollowed and/orraised portion to be formed.

The method according to another aspect of the invention comprises apress die having a flat press surface.

A soft material, such as silicon rubber, is used for the press die inthe above-described method. Even if the press die has a flat presssurface, it is possible for the softened area of the tube to trace theshape of the mold portion, provided that the irregularity is relativelyshallow or low. The equipment cost concerning the press die can bereduced. The press die is not necessarily required to fit in preciselywith the mold portion. Therefore, production efficiency can bemaintained at a high level.

The method according to another aspect of the invention comprises usinga press die having a press surface that roughly fits in with the shapeof the mold portion.

The above-described method is effective to reproduce the shape of themold portion in the tube wall even if the mold portion has a relativelydeep up-and-down pattern. Thus, a hollowed and/or raised portion, whichis identical with the shape of the mold portion, can be formedreproducibly in the tube wall.

The method according to another aspect of the invention comprises themandrel having a hollowed mold portion in a part of the outer surface ofthe mandrel and that the hollowed mold portion in turn gives rise to ahollowed portion in the tube wall.

The above-described method utilizes a bottomed cylindrical mandrel,which has a hollowed mold portion to be formed in a part of surface ofthe mandrel, and which is also provided with small through-holes in thismold portion. The mandrel is inserted in the synthetic resin tube, andthe inner wall of the tube is brought in contact with the mandrel. Thetube is then heated and softened in the portion facing this mold portionunder the condition that the mandrel has been inserted in the tube. Thisheating operation creates thermal shrinkage in the softened area. As aresult, the periphery of the softened area of the tube comes in closecontact with the curved outer surface of the mandrel in the areasurrounding the mold portion. Because of this close contact, deaerationproceeds effectively from the through-holes to the central opening ofthe mandrel. The softened portion is molded in the manner similar tovacuum-molding so as to trace the shape of the mold portion. Thus, itbecomes possible to form a hollowed portion in a fairly wide area of thetube.

The synthetic resin tube is usually molded by extruding a syntheticresin in a cylindrical shape or by joining the longer sides of a filmtogether and adhering the overlap portion along these sides. When thetube is heated and softened, there occurs thermal shrinkage enough togive tightness in the above-described contact.

In the case of the molding carried out in the manner similar to vacuummolding, the softened resin deforms relatively uniformly in all thesoftened area. There is no occurrence of partially biased resin drawing,and an attractively hollowed portion can be molded smoothly.

The tube is in the undercut engagement with the mandrel due to thehollowed portion that has been formed. This tube is usually squeezableand is largely made of a relatively soft synthetic resin. After thehollowed portion has been formed, the tube can be pulled and separatedfrom the mandrel relatively easily, though the undercut portion isdeformed to some extent at the time of pull.

The hollowed portion is first formed in the tube wall in the mannersimilar to vacuum molding, and then the press die of a soft material(hereinafter referred to as the “core mold”) having the shapecorresponding to the hollowed mold portion and roughly the same size isthrust onto the softened portion of the tube in the manner similar topress molding. This operation ensures that the shape of the mold portionis reproducibly transcribed to the tube. The periphery of the hollowedportion thus obtained is in the shape of clear-cut edges, which areaesthetically attractive.

It should be noted here that, even if the molding were attempted fromoutside only by means of the core mold in the manner similar to pressmolding, no attractive hollowed portion would be formed smoothly. Thisis because the softened resin tends to deform disproportionately at theedges of the core mold. But if the softened portion is first allowed totake roughly the shape of the hollowed mold portion in an operationsimilar to vacuum molding before the softened portion is processed inthe manner similar to press molding, then the hollowed portion can beformed smoothly, with resultant clear-cut edges being highlyreproducible.

The method according to another aspect of the invention comprises thehollowed mold portion having such a shape that the depth of the moldgradually changes in a tapered manner in the axial direction of themandrel.

Because based on the above method, the hollowed mold portion has such ashape that the depth of the mold gradually changes in a tapered mannerin the axial direction of the mandrel, the tube can be pulled out of themandrel smoothly after the hollowed portion has been formed and cooled.

The method according to another aspect of the invention comprises themandrel having a raised mold portion in a part of the outer surface andthat this mold portion serves to form a raised portion in the tube wall.

The above-described method utilizes a raised mold portion in a part ofthe outer surface of the mandrel. The processing in the manner similarto vacuum molding, or a combination thereof with the processing in themanner similar to press molding, can be used to change a part of thetube wall so as to form a raised portion in a fairly wide area of thetube.

The method according to another aspect of the invention comprises themandrel having a hollowed and raised mold portion in a part of the outersurface and that this mold portion serves to form a hollowed and raisedportion in the tube wall.

The above-described method utilizes the hollowed and raised mold portionin a part of the outer surface of the mandrel. The processing in themanner similar to vacuum molding, or a combination thereof with theprocessing in the manner similar to press molding, can be used to changea part of the tube wall so as to form a hollowed and raised portion in afairly wide area of the tube. Such a hollowed and raised portion can beused to display characters, graphic figure, or a design.

The method according to another aspect of the invention comprises atleast one of the hollowed and/or raised portions is formed so as to havea label function for the purpose of recognition.

According to theabove-described method, it is possible to display atrade name, a product name, etc., by means of the shapes of a hollowedand/or raised portion. Both the shape and number of the hollowed and/orraised portion or portions can be effectively utilized to make theproduct recognizable not only visually, but also by touch with a hand,as needed, for example, in the dark place. It is also possible to printa character or characters or attach a label on the hollowed portion soas to make the display much more impressive.

The method according to another aspect of the invention comprises ashape of the hollowed and/or raised portion is formed in the tube wallso that such a shape has a label function for a decorative purpose.

The above-described method is not used merely to emboss an up-and-downpattern on the tube wall. This method involves changing the shape of apart of the tube so as to form a hollowed and/or raised portion in afairly wide area of the tube. A decorative effect not so far experiencedcan be expected. If this hollowed and/or raised portion is combined withprinting, hot stamping, or label attachment, the tube will have animproved decorative effect.

The means of carrying out one aspect of the invention comprises atubular container having a shape of the hollowed and/or raised portion,which is molded in the body wall of a tubular container in a mannersimilar to vacuum molding.

The means of carrying out another aspect of the invention comprises atubular container having at least a shape selected from a hollowedportion, a raised portion, and a hollowed and raised portion, all ofwhich are molded in the body wall in the manners similar to vacuummolding and press molding that follows the vacuum molding.

Under the above-described configurations, the shape of a part of tubewall is changed to provide a tubular container having a non-conventionalhollowed and/or raised portion. The tubular container thus provided hasdecorativeness, appearance, or functionality that has never beenachieved before.

EFFECTS OF THE INVENTION

This invention having the above-described configuration has thefollowing effects:

The heating operation creates thermal shrinkage in the softened area. Asa result, the periphery of the softened area of the tube comes in closecontact with the outer surface of the mandrel in the area surroundingthe mold portion. Because of this close contact, deaeration proceedssmoothly from the through-holes to the central opening of the mandrel.The softened area is molded in a manner similar to vacuum-molding so asto trace the shape of the mold portion. Therefore, it is possible tochange the shape of a part of the tube wall and to form a hollowedand/or raised portion in a fairly wide area of the tube.

In the case of the molding carried out in a manner similar to vacuummolding, the softened resin deforms relatively uniformly because theresin is pulled from inside over the entire softened area. There is nooccurrence of partially biased resin drawing, and the softened portioncan be molded to trace the shape of the mold portion, while minimizingwrinkle formation. Therefore, it is possible to mold an attractivelyhollowed and/or raised portion smoothly.

A press die is thrust onto the softened area of the tube in a mannersimilar to press molding. This operation ensures that the shape of thehollowed and/or raised mold portion of the mandrel is reproduciblytranscribed to the tube. For example, the shape of clear-cut edges, themeticulous up-and-down pattern of characters, etc., are quitereproducibly formed. The hollowed and/or raised portion thus obtainedhas an attractive, well functioning shape.

The press die of silicon rubberis used. Such a press die is suitablebecause of durability, fitness of the press die to trace the shape ofthe mold portion that has been hollowed and/or raised, and releasabilityfrom the softened area of the tube. The silicon rubber press dieimproves productivity and enables quite an attractively hollowed and/orraised portion to be formed.

A press die having a flat press surfaceis used. A soft material, such assilicon rubber, is used for the press surface. Even if the press diewith a flat press surface is used, it is possible for the softened areaof the tube to trace the shape of the mold portion, on the conditionthat the irregularity is relatively shallow or low. The equipment costfor the press die can be reduced. The press die is not necessarilyrequired to fit in precisely with the mold portion. Therefore,production efficiency can be maintained at a high level.

Use is made of a press die having a press surface that roughly fits inwith the shape of the mold portion. Such a press die is effective toreproduce the shape of the mold portion in the tube wall even if themold portion has a relatively deep up-and-down pattern. Thus, a hollowedand/or raised portion, which is identical with the shape of the moldportion, can be formed reproducibly in the tube wall.

As a result of thermal shrinkage, the periphery of the softened area ofthe tube comes in close contact with the outer surface of the mandrel inthe area surrounding the hollowed mold portion. Because of this closecontact, deaeration proceeds effectively from the through-holes to thecentral opening of the mandrel. The softened portion is molded in themanner similar to vacuum molding so as to trace the shape of thehollowed mold portion. Therefore, it becomes possible to change a partof the tube wall so as to form a hollowed portion in a fairly wide areaof the tube.

In the case of the molding carried out in the manner similar to vacuummolding, the softened resin deforms relatively uniformly in all thesoftened area. There is no occurrence of partially biased resin drawing,and an attractively hollowed portion can be molded smoothly.

The hollowed mold portion has such a shape that the depth of the moldgradually changes in a tapered manner in the axial direction of themandrel. Under this configuration, the tube can be pulled out of themandrel smoothly after the hollowed portion has been formed and cooled.

A raised mold portion is formed in a part of the outer surface of themandrel, and is used to change a part of the tube wall so as to form araised portion in a fairly wide area of the tube, by processing the tubein the manner similar to vacuum molding, or combining this processingwith the processing in the manner similar to press molding.

A hollowed and raised mold portion is formed in a part of the outersurface of the mandrel, and is used to change a part of the tube wall soas to form a hollowed and raised portion in a fairly wide area of thetube, by processing the tube in the manner similar to vacuum molding, orcombining this processing with the processing in the manner similar topress molding. This hollowed and raised portion can be used to expresscharacters or figures.

It is possible to display a trade name, a product name, etc., by meansof the pattern of a hollowed and/or raised portion. Both the shape andnumber of the hollowed and/or raised portion or portions can beeffectively utilized to make the product recognizable not only visually,but also by touch with a hand, as needed, for example, in the darkplace. It is also possible to print a character or characters or attacha label onto the hollowed portion so as to make the display much moreimpressive.

An up-and-down pattern is not merely embossed on the tube wall, but apart of the tube wall is changed in its shape so as to form a hollowedand/or raised portion. Therefore, a decorative effect not so farexperienced can be expected.

The shape of a part of tube wall is changed to provide a tubularcontainer having an attractively hollowed and/or raised portion orportions. The tubular container thus provided has decorativeness,appearance, or functionality that has never been achieved before.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an explanatory diagram showing, in vertical sections, theprocessing method in the first embodiment of this invention;

FIG. 2 is a perspective view of a part of the mandrel to be used in theprocessing method shown in FIG. 1;

FIG. 3 is a front elevational view of an example of the tubularcontainer of this invention obtained by the processing method shown inFIG. 1, wherein the bottom is not yet sealed;

FIG. 4 is a side elevational view of the tubular container shown in FIG.3;

FIG. 5 is a side elevational view of the tubular container shown in FIG.3, wherein the bottom has been sealed;

FIG. 6 is an explanatory diagram showing, in a vertical section, aprocess step in the second embodiment of the processing method accordingto this invention;

FIG. 7 is a perspective view of a part of the mandrel to be used in theprocessing method shown in FIG. 6;

FIG. 8 is an explanatory diagram showing, in a vertical section, aprocess step in the third embodiment of the processing method accordingto this invention;

FIG. 9( a) is a perspective view of a part of the mandrel to be used inthe processing method shown in FIG. 8; FIG. 9( b), a plan view showingthe detail of the hollowed and raised mold portion shown in FIG. 9( a);and FIG. 9( c), a vertical section taken from line A-A in FIG. 9( b);and

FIG. 10 is a front elevational view of another example of the tubularcontainer of this invention, obtained by the processing method shown inFIG. 8, wherein the bottom is not yet sealed.

DETAILED DESCRIPTION OF EMBODIMENTS

This invention is further described with respect to preferredembodiments, now referring to the drawings. FIGS. 3-5 show a tubularcontainer obtained by the method of processing a synthetic resin tube inthe first embodiment of this invention. FIGS. 3 and 4 are front and sideelevational views, respectively, of a tubular container, which shows thebottom that is not yet sealed. FIG. 5 is a side elevational view of thetubular container having bottom seal 7. This tubular container is 25 mmin inner bore and 150 mm long.

As shown in FIG. 3, this tubular container 1 comprises a cylindricaltube 2, from which body 6 is made, and head 3, which includes shoulder 5and neck 4. The head 3 is fitted to one end of the tube 2 integrally bymeans of injection molding or compression molding. The tube is filledwith contents through the other end, and bottom seal 7 (See FIG. 5) isformed at this end.

The tube 2 is a laminated product obtained by multi-layer extrusionmolding. Outer layer is made of a low-density polyethylene resin; andinner layer, a high-density polyethylene resin. Both the outer and innerlayers have a wall thickness in the range of 200 to 250 microns.

The molding of the head 3 requires simultaneous adhesion to one end ofthe tube 2.

In one method, the tube 2 is fitted around the mandrel 11, wherein atthe end of the mandrel the core mold for head 3 is formed.

Under this condition, the tube 2 and the mandrel together are insertedin the cavity where molten resin has been supplied. The resin is thencompressed to mold the head 3 and to adhere the head 3 to the tube 2.

Or under above condition, the material used to form the head 3 isextruded in advance in the shape of a plate. The molten state plate isplaced between the core mold and the cavity mold, and is punched out bythe cutter that surrounds the tube 2. The punched plate is pushed intothe cavity mold by the core mold, and the head 3 thus formed is thenwelded to the end of the tube 2.

Or under above condition, the head 3 is molded by injecting moldingwherein molten resin is injected into the cavity formed between the coremold and the cavity mold.

FIG. 1 is an explanatory diagram showing the processing method in thefirst embodiment of this invention. FIG. 2 is a perspective view of themandrel 11 used in this embodiment. The mandrel 11 has a bottomedcylindrical shape. A hollowed mold portion 13, i.e., one of the shapesof the hollowed and/or raised mold portion 12, is formed in a part ofthe outer surface of the mandrel 11 in such a way that the depth of thehollowed mold portion 13 is reduced in a tapered manner along the axialdirection of the mandrel 11. The central opening 16 is connected to avacuum pump to enable the tube to be processed in a manner similar tovacuum molding, by utilizing many small through-holes 17 drilled in thehollowed mold portion 13.

The method of molding a hollowed portion 8 in the wall of the tube 2 inthis embodiment is described in accordance with the process flow shownin FIG. 1( a) through FIG. 1( e). FIG. 1( a) shows the mandrel 11 thathas been inserted in the tube 2 in loose contact with the inner tubewall. Because of this loose contact, the mandrel 11 can be insertedeasily. In addition, the tight contact of the mandrel 11 with thesoftened resin is secured on the periphery of the hollowed mold portion13 at the time when resin is softened, as later described.

In many cases, as described above, the head 3 is adhered to the tube 2under the condition that the mandrel 11 has been inserted in the tube 2.In this embodiment, however, the head 3 is adhered to one end of thetube 2 by the method described above, and then the mandrel 11 isinserted in the tube 2 through the other end of the tube 2.

Then, the resin is softened by heating the tube 2 from outside in theapproximate area that faces the hollowed mold portion 13. This heatingprocess creates thermal shrinkage in the softened area. As a result, theperiphery of the softened area in the wall of the tube 2 comes in closecontact with the curved outer surface of the mandrel 11 in the areasurrounding the hollowed mold portion 13 (See the close-contact area 29in FIG. 1( b)). Because of this close contact, deaeration proceedssmoothly from the small through-holes 17 to the central opening 16 ofthe mandrel 11. The softened portion is molded in a manner similar tovacuum-molding so as to trace the shape of the hollowed mold portion 13.Therefore, it is possible to form a hollowed portion 8 in a fairly widearea. Preferably, the softened area is somewhat wider than the hollowedmold portion 13 to make the contact sufficient (See FIG. 1( b)).

The tube 2 is heated in this embodiment by hot air 27 a from aheater/cooler 26. The resin is softened under the blow of hot air 27 a,and the close contact of the softened resin with the mandrel 11 can beachieved easily. The heating means is not restricted to this hot air 27a, but the heating with an infrared heater, etc., is also an effectivemeans.

Air is evacuated from inside the mandrel 11 by means of a vacuum pump.The space between the softened resin wall and the hollowed mold portion13 is thus deaerated through the small through-holes 17 (See blackarrows showing the direction of deaeration in FIG. 1( c)). Now thesoftened resin takes the shape approximately tracing the shape of thehollowed mold portion 13 due to the operation similar to vacuum molding.At this stage, though, edges 18 may not be formed reproducibly well(FIG. 1( c)).

Under the configuration of this embodiment, many small through-holes 17in the shape of small, round holes are disposed over the entire area ofthe hollowed mold portion 13. The shape, number, and layout of thesesmall through-holes 17 can be determined by giving consideration to theshape of the entire mold portion 12 and the shape of edges 18. Forexample, clear-cut edges 18 can be formed more favorably in the wall ofthe tube 2 by disposing slit-like small through-holes 17 along the moldarea that faces these edges 18.

A pressing block 21 is provided with a core mold 23 of silicon rubber,which serves as the press die 22, and of which press surface has theshape approximately fitting in with the shape of the hollowed moldportion 13. When this pressing block 21 is lowered, the softened resinis thrust onto the hollowed mold portion 13 in the manner similar topress molding, while continuing deaeration by means of the vacuum pump.At that time, the shape of the hollowed mold portion 13 including theedges 18 is transcribed to the tube 2 in a fully reproducible manner,and thus the hollowed portion 8 is formed in the tube wall (See FIG. 1(d)).

The shape and size of the core mold 23 are matching with those of thehollowed mold portion 13 in this embodiment. However, appropriate shapeand size can be determined and used, as by utilizing a larger or smallercore mold 23 or by sharpening the edges, while giving consideration tothe shape of the hollowed mold portion 13, including the details ofedges, such as the arc of the edges, and reproducibility of thetranscribed shape or moldability in the operation similar to pressmolding. Since the core mold 23 is made of a soft material, the coremold 23 of a somewhat larger size can be fitted in the hollowed moldportion 13, though there is a limit, of course.

The core mold 23 is then released. After cooling with cooling air fromthe heater/cooler 26, the tube 2 is pulled out of the mandrel 11 (SeeFIG. 1( e).). It is preferred that the tube 2 is cooled, with deaerationcontinued by means of the vacuum pump, to prevent the hollowed portion 8from deforming during the cooling. Cooling air 27 b is used to cool thetube 2 in this embodiment, giving consideration to the reproducibilityof the shape of edges 18. But the tube 2 can be left to cool in ambientair, depending on the shape of the mold portion 12.

The hollowed portion 8 thus formed leaves the tube 2 to be in theundercut engagement with the mandrel 11. However, the hollowed moldportion 13 has such a shape that a gradual, shallow slope is formed in atapered manner from the bottom of the hollow in the axial direction ofthe mandrel 11. Because of this shape, the tube 2 can be extractedsmoothly from the mandrel 11 after the formation and cooling of thehollowed portion 8 (See the outline arrow 28 showing the direction ofextraction in FIG. 1( e)).

FIGS. 6 and 7 illustrate the processing method in the second embodimentof this invention, showing a raised portion 9 in the wall of the tube 2.The steps of the processing method are similar to those of the firstembodiment shown in FIG. 1. FIG. 6 shows a molding process similar tovacuum molding that corresponds to FIG. 1( c). FIG. 7 is a perspectiveview of the mandrel 11 used in the second embodiment. A raised moldportion 14 is an elliptical mold portion 12, and is formed in a part ofouter surface of the mandrel 11. A number of small through-holes 17 aredisposed inside as well as outside of the periphery.

The mandrel 11 having a raised mold portion 14 is inserted in the tube 2to form a raised portion 9. Since the wall of the tube 2 is thin andflexible, the mandrel 11 can be easily inserted in the tube 2 by givingthe shape of a steeple head to the inserting end of the mandrel 11.

Under the condition that the mandrel 11 has been inserted in the tube 2,there occurs some gap between the tube 2 and the outer surface of themandrel 11. The resin of the tube 2 softens under hot air 27 a (See FIG.1( b)), and the heated resin contracts in and around the softened area.As a result, the tube wall comes in tight contact with the outer surfaceof the mandrel 11 on the periphery of the area of the raised moldportion 14. Because of this close contact, deaeration by means of thevacuum pump proceeds effectively. The softened portion is molded in amanner similar to vacuum molding so as to trace the shape of the raisedmold portion 14. Therefore, a raised portion can be formed in a fairlywide area of the tube 2.

Especially, if there occurs a somewhat wider gap between the tube 2 andthe outer surface of the mandrel 11, as found in this embodiment, then acap is screwed onto the neck 4 to seal the neck and to facilitatedeaeration by means of the vacuum pump effectively.

This second embodiment includes a process step of pressing softenedresin onto the raised mold portion 14 in the manner similar to pressmolding, while continuing deaeration by means of the vacuum pump. Thisstep is carried out to sharpen especially the shape of the edges 18, byutilizing a pressing block 21 provided with a silicon rubber press die22, with its press surface having the shape roughly fitting in with theshape of the raised mold portion 14. In some cases, the raised portion 9can be fully reproducible simply through the processing similar tovacuum molding, depending on the shape of the entire raised mold portion14 or the shape of the edges 18.

FIG. 10 is a front elevational view of another example of tube containerof this invention, provided by the third embodiment of the processingmethod of this invention. The tube container of FIG. 10 shows the bottomwhich is not yet sealed. The tube container has the appearance similarto the container shown in FIG. 3, but has a hollowed and raised portion10 formed in the front.

More particularly, the above-described hollowed and raised portion 10comprises an elliptical hollowed portion 10 a, a round raised portion 10b, and an embossed character pattern area 10 c, which is formed insidethe round raised portion 10 b and contains an embossed alphabeticalletter or letters displayed like an emblem. Inside this embossedcharacter pattern area 10 c there is a hot-stamped character orcharacters 10 d, which look as though the character or characters havebeen embossed. Under this configuration, this tube has a display anddecorative effect that has never been experienced before.

FIGS. 8 and 9 show the processing method in the third embodiment of thisinvention. This method is used to form the hollowed and raised portion10 shown in FIG. 10. The procedure is basically similar to that of thefirst embodiment shown in FIG. 1. FIG. 8 shows a molding process similarto vacuum molding that corresponds to FIG. 1( c).

FIG. 9 show the mandrel 11 to be used in this third embodiment, in which9(a) is a perspective view; 9(b) is a plan view showing the detail ofthe hollowed and raised mold portion 15 of FIGS. 9( a); and 9(c) is avertical section taken along the line A-A shown in 9(b). The hollowedand raised mold portion 15 is formed as a mold portion 12 in the outersurface of the mandrel 11. Small through-holes 17 are disposed in thehollowed and raised mold portion 15 and also around the peripherythereof. Among FIG. 9, the embossed character pattern area 15 c is notshown in FIG. 9( a); and the through-holes 17 are not shown in FIGS. 9(b) and 9(c), for the purpose of simplification.

The hollowed and raised mold portion 15 comprises an elliptical hollowedmold portion 15 a, a round raised mold portion 15 b, and an embossedcharacter pattern area 15 c, which is formed inside the round raisedportion 10 b and contains an alphabetical letter or letters displayedlike an emblem.

As shown in FIG. 8, the mandrel 11 having the embossed character patternarea 15 c is inserted in the tube 2 for the processing of the hollowedand raised portion 10. Usually, there occurs some gap between the tube 2and the outer surface of the mandrel 11 in the part other than thehollowed and raised mold portion 15. However, similarly as in the secondembodiment, the resin softens, and the heated resin contracts in andaround the softened area. As a result, the tube wall comes in tightcontact with the outer surface of the mandrel 11 on the periphery of thehollowed and raised mold portion 15 of the mandrel 11. Because of thisclose contact, deaeration by means of the vacuum pump proceedseffectively. Therefore, the hollowed and raised portion 10 can be formedby deforming the wall of the tube 2.

Also in this embodiment, the press die 22 is thrust onto the hollowedand raised portion 15 in the manner similar to press molding so that theshape of edges of the embossed character pattern area 15 c, etc., issharpened. The press die 22 having a flat press surface is used in thisembodiment. If the up-and-down pattern is relatively shallow and low,the press die 22 having the flat press surface made of silicon rubber,such as the one used in this embodiment, is deformable to fit in withthe shape of the hollowed and raised mold portion 15. Thus, the shape ofthe mold portion 12 can be transcribed smoothly to the tube 2. Sincethere is no need of delicate die matching between the mold portion 12and the press die 22, high production efficiency is available for theprocessing steps, especially where there is a meticulous up-and-downpattern, such as found in the embossed character pattern area 15 c ofthis embodiment.

If a hollowed and raised portion 10, such as the one shown in FIG. 10,is to be formed, a letter or letters 10 d are hot-stamped beforehand onthe tube 2. Then, the processing method of this embodiment is used toform the embossed character pattern area 10 c so as to fit in with theletter or letters 10 d. Naturally, the letter or letters can be printedinstead of hot stamping. An identifying function can also be given tothe tube 2 so that the tube 2 may be distinguished to the touch by hand.This can be done by utilizing the embossed character pattern area 10 cof this embodiment, or differences in the shape, such as circle orsquare, and in the number, of any other hollowed and raised portions.

The method of processing a tube to form a hollowed and/or raised portionin the tube wall does not limit itself to the use with the tubularcontainer that has been taken up in the above-described embodiments, butcan be applied generally to the containers that utilize cylindricalshapes for the container body. For example, a cup container, in which tofill coffee drink, is obtained by adhering thermally the bottom to acylindrical body. Such a cup container can also be processed by themethod of forming the hollowed and/or raised portion according to thisinvention. Thus, tubular or cylindrical containers are provided, whichhave excellent decorativeness, appearance, or functionality that has notbeen found before.

In many cases, laminated tubular containers are used, in which analuminum layer is laminated in such a construction aspolyethylene-aluminum-polyethylene. Since the aluminum layer is usuallythin, a hollowed and/or raised portion can be formed in the wall of thealuminum-laminated tube by combining the molding similar to vacuummolding with the molding similar to press molding, just as the samecombination is utilized in the method of forming the above-describedhollowed and/or raised portion in the single-layer tube wall.

INDUSTRIAL APPLICABILITY

According to the processing method of this invention, it is possible toprovide a tubular container having an attractively hollowed and/orraised portion or portions formed in a part of the outer surface of thetube. In the field of cosmetics, etc., there will be an increasing rangeof uses for this promising tubular container.

1. A method of processing a fully formed synthetic resin tube, whichcomprises: inserting a mandrel into the fully formed synthetic resintube while bringing an inner wall of the fully formed synthetic resintube into contact with the mandrel, wherein the mandrel is a bottomedcylindrical mandrel that is closed at one end, the mandrel having afirst mold portion and a second mold portion, wherein the second moldportion has a shape formed in a non-circumferential part of an outersurface of the mandrel, which does not extend around an entirecircumference of the mandrel, the shape being selected from a hollowedshape, a raised shape, and a hollowed and raised shape that is differentthan a shape of the first mold portion, the second mold portion havingsmall through-holes for applying force; heating and softening an area ofthe fully formed synthetic resin tube in and around an area facing thesecond mold portion after inserting the mandrel into the fully formedsynthetic resin tube; allowing a peripheral portion of the heated andsoftened area to surround an entire edge of the second mold portion andto come into tight contact therewith, as caused by thermal shrinkageinvolved in the heating and softening the area of the fully formedsynthetic resin tube; after coming into tight contact with the secondmold portion by the thermal shrinkage, deaerating the fully formedsynthetic resin tube via a central opening and the small through-holesof the second mold portion to mold the heated and softened area of thefully formed synthetic resin tube by vacuuming air in the fully formedsynthetic resin tube; and forming in the heated and softened area of thefully formed synthetic resin tube at least one portion selected from ahollowed portion, a raised portion, and a hollowed and raised portion.2. The method of processing a fully formed synthetic resin tube,according to claim 1, wherein at least one of the at least one shapeselected from the hollowed portion, the raised portion, and the hollowedand raised portion is formed in the wall of the fully formed syntheticresin tube by vacuuming air in the fully formed synthetic resin tube,and wherein a press die made of a soft material is thrust onto theheated and softened area of the fully formed synthetic resin tube bypressing the press die onto the heated and softened area of the tube. 3.The method of processing a fully formed synthetic resin tube, accordingto claim 2, wherein the press die is made of silicon rubber.
 4. Themethod of processing a fully formed synthetic resin tube, according toclaim 2, the press die has a flat press surface.
 5. The method ofprocessing a fully formed synthetic resin tube, according to claim 2,further comprising using the press die, the press die having a presssurface that roughly fits in with the shape of the second mold portion.6. The method of processing a fully formed synthetic resin tube,according to claim 1, wherein the mandrel has a hollowed second moldportion in a part of the outer surface, and wherein the hollowed secondmold portion forms a hollowed portion in the wall of the fully formedsynthetic resin tube.
 7. The method of processing a fully formedsynthetic resin tube, according to claim 6, wherein the hollowed secondmold portion has such a shape that a depth of the hollowed second moldportion changes gradually in a tapered manner in an axial direction ofthe mandrel.
 8. The method of processing a fully formed synthetic resintube, according to claim 1, wherein the mandrel has a raised second moldportion in a part of the outer surface, and wherein the raised secondmold portion forms a raised portion in the wall of the fully formedsynthetic resin tube.
 9. The method of processing a fully formedsynthetic resin tube, according to claim 1, wherein the mandrel has ahollowed and raised second mold portion in a part of the outer surface,and wherein the hollowed and raised second mold portion forms a hollowedand raised portion in the wall of the fully formed synthetic resin tube.10. The method of processing a fully formed synthetic resin tube,according to claim 1, wherein at least one of the at least one portionselected from the hollowed portion, the raised portion, and the hollowedand raised portion is formed so as to have a label function forrecognition.
 11. The method of processing a fully formed synthetic resintube, according to claim 1, wherein at least one of the at least oneportion selected from the hollowed portion, the raised portion, and thehollowed and raised portion is formed so as to have a label function fora decorative purpose.